Unix Timestamp in .NET

In one of my current projects, I’m required to calculate Unix Timestamps in my .NET classes. Unix Timestamp is defined as number of second elapsed since January 1, 1970 00:00:00.

.NET also provides a very useful class System.DateTime for Date and Time calculation. Unlike Unix standard, DateTime type in .NET represents date and time values from 12:00:00 midnight, January 1, 0001 A.D. through 11:59:59 P.M., December 31, 9999 A.D. measured in 100-nanoseconds units called Ticks.

Using above facts, here is the simple code for DateTime conversion between these two standards:

long ToUnixTimestamp(System.DateTime dt)
{
    DateTime unixRef = new DateTime(1970, 1, 1, 0, 0, 0);
    return (dt.Ticks - unixRef.Ticks) / 10000000;
}
DateTime FromUnixTimestamp(long timestamp)
{
    DateTime unixRef = new DateTime(1970, 1, 1, 0, 0, 0);
    return unixRef.AddSeconds(timestamp);
}

Economical Numbers

There are 10^11 stars in the galaxy. That used to be a huge number. But it’s only a hundred billion. It’s less than the national deficit! We used to call them astronomical numbers. Now we should call them economical numbers.

–
Richard Feynman